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Coating for aluminum heat sink
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I have an aluminum heat sink used in a cleanroom environment and therefore the surface needs to sealed to prevent oxidation and contamination to sensitive materials. Will a chromate coating have sufficient thermal conductivity to ensure good heat transfer? And is chromate a sacrificial coating or will it resist oxidation even if scratched? If the answer to these questions is 'no' than what would be the best coating to use?
Jim SbrognaSemiconductor Equipment Engineer - Natick , Massachusetts
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Heat sinks can be anodized. Chromate coatings will not cause thermal conductivity problems, but they are electrically conductive, which could be a problem or not. Chromate is not a sacrificial coating but it is "self healing" so it is helpful even in an environment where scratching is possible.
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 Ted Mooney, P.E. finishing.com Brick, New Jersey |
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In addition to all the accurate advice Ted sent to you, you may need also to know that bare unpainted chromate conversion coatings are limited to a surface temperature of 140 F, above which the coatings disintegrate. Absolutely not suitable for a very hot sink.
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Robert H Probert Robert H Probert Technical Services  Garner, North Carolina
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The coating of choice for heat sinks has been electroless nickel forever. Corrosion resistant, conductive, both thermal and electrical. Even looks good.
Dan Weaver- Toccoa, Georgia
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Anodizing should be fine. Aluminum oxide is tough, proven, and is thermally a good conductor due to lattice phonon effects.
Dale Woika- Bellefonte, Pennsylvania, USA
April 8, 2011
sir if I want to increase heat transfer capacity of heat sink, electroless nickel coating will be ok, or you can suggest any other coating?
Hemant jakhwal- udaipur,rajasthan,india
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Electroless nickel is the best coating if you want maximum heat transfer. Anodize coatings are dielectric and have poor heat transfer characteristics. They are very corrosion resistant as is electroless nickel.
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Don Baudrand Don Baudrand, Consultant Poulsbo, Washington |
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